JP4900618B2 - Imaging element, display device - Google Patents

Description

  The present invention relates to an imaging element that forms a real image in the air on the surface opposite to the projection object in an optical element using specular reflection by a micromirror, and a display apparatus including such an imaging element. Is.

  2. Description of the Related Art Conventionally, an aspect using, for example, a convex lens or a concave mirror is known as an optical element used to form a three-dimensional or two-dimensional object or image as a real image at a spatially moved position. However, in order to meet the demand for ensuring an appropriate viewing angle, an optical element with a large width is required, and on the other hand, it is difficult to use an optical element with a short focal length due to aberrations and other problems. However, the depth dimension of the optical system also becomes long, and there is a problem that the device using the optical element becomes enormous, and consequently the display device itself using the optical element increases in size. Further, even if the device is enlarged, it is difficult to completely eliminate the aberration. When the viewpoint is changed, the spatial position of the real image changes and the image with respect to the three-dimensional object is distorted.

  In order to solve such problems, an aerial video display device using a microlens array has recently been developed (see, for example, Patent Document 1). This utilizes an erecting equal-magnification imaging system for a two-dimensional image, and the spatial parallelism of the two-dimensional image without distortion by an optical device having the same size as the display surface for displaying the two-dimensional image. It is possible to move. If it is such, compared with a normal lens, size reduction and thickness reduction of an optical device can be achieved, and it contributes also to compactization of a display apparatus. However, this cannot obtain a real image of a three-dimensional object.

Therefore, an optical element has been proposed in which each optical system constituting the erecting equal-magnification imaging optical element used in the above system is an afocal optical system with an infinite focal length. (For example, refer to Patent Document 2). This optical element is capable of forming a mirror image of a projection object as a real image, and uses the refractive action of light by a lens as its basic principle. It shall be called a video imaging element. Note that forming a mirror image means that a real image of a three-dimensional object can be formed without distortion. The refractive real mirror image forming element is arranged on the same optical axis with the focal lengths of the first lens element and the second lens element being spaced apart from each other to form an afocal optical system, and an incident lens of the afocal optical system The surface and the exit lens surface are arranged in the same plane in an array, and the combination of the first lens element and the second lens element is two convex lenses, and two optical fiber lenses. Have been proposed.
JP-A-2005-234240 Japanese Patent Laying-Open No. 2005-010755

  By the way, in the case of a refraction type real mirror image forming element using refraction by a lens, it is necessary to arrange or assemble high-precision microlenses with high accuracy, resulting in a problem that the structure is complicated and the cost is increased. . Further, since it is necessary to focus at least once in the optical element by the lens action, the thickness of the element cannot be reduced so much. Further, since it uses the refraction of light, it can be observed only from a direction substantially perpendicular to the element surface, and it is difficult to observe an image with a large angle from an oblique direction to the element surface. There is a problem.

  The present invention has been made paying attention to such problems. The main purpose of the present invention is to simplify the structure and reduce the cost by using a mirror surface having a reflecting action. An imaging element using a micromirror, which is an optical element that can be made thin and can be observed at an angle to the element surface, and a display device including such an imaging element It is to provide.

In other words, the imaging element according to the present invention is an optical element that causes bending of a light beam when light passes through an element surface constituting one plane, and is disposed at an angle perpendicular to or close to the element surface. A plurality of unit optical elements that function as two-surface corner reflectors that reflect light by two mirror surfaces that are perpendicular to each other, and a projection object that is disposed at an arbitrary position in one space across the element surface surface of the object to be projected with respect to the element surface by the light beam emitted from the when passing through the respective unit optical elements, once in each of the two mirror in each unit optical element, reflects a total of two and characterized in that the symmetrical position is configured to form an image of the object to be projected, and from the perspective angled in an oblique direction with respect to the element surface adapted to observe the image formed by the two reflection That.

  In such a case, by appropriately setting the number and arrangement of mirror surfaces constituting the unit optical element, when the light passes through the element surface, it is reflected by each mirror surface in the plurality of unit optical elements. Thus, an object or an image arranged in one space across the element surface can be imaged as a real image in the opposite space. Therefore, compared to conventional optical elements that require a plurality of high-precision microlenses, it is made with a mirror surface with a planar structure, so the structure can be simplified, the cost can be reduced, and the thickness can be reduced. It can respond flexibly. In addition, since the mirror surface is provided substantially perpendicular to the element surface, the light beam can be bent at a steep angle on the element surface, so that the formed real image is observed at an angle to the element surface. It becomes possible to do. Therefore, an object arranged in one space on the element surface or a projection object composed of a projected image can be observed as a standing image standing on the element surface on the opposite side. Further, the mirror surface may be provided just perpendicular to the element surface, or provided in an angular range of several degrees before and after it can be regarded as being substantially vertical. Since the three-dimensional image or the real image of the two-dimensional image formed through the imaging element is formed in the air, it can be touched or pointed with a finger or the like, and it can be viewed obliquely with respect to the element surface. Since observation is possible, it is possible to provide a novel image observation method that has never existed as an aerial image floating on a plane. However, the real image of the three-dimensional image is a reverse view image with the depth reversed. For this reason, it is necessary to take measures such that the real object is transmitted twice through the imaging element, and the synthesized three-dimensional image is inverted in depth.

The preferred configuration of the unit optical element with a simple structure for obtaining a real image as the imaging element is provided with two mirror surfaces, and light transmitted through the unit optical element is reflected once by the two mirror surfaces. and in order to form an image on the opposite side of the element surface is, the two mirror surfaces constituting the unit optical element are perpendicular to each other will be made to function as dihedral corner reflector, imaging of the real image of the specular image It becomes a reflection type real mirror image formation element which can perform.

Further, regarding the arrangement of the unit optical element, even if the above-described two-surface corner reflector is arranged in a plurality of directions on the element surface, the light is retroreflected in the element surface direction. The image is formed at the same position regardless of the direction. On the other hand , when unit optical elements having two mirror surfaces that are not orthogonal but not parallel are used, functionally identical unit optical elements in which the angles formed by the two mirror surfaces are equal in all unit optical elements In the same manner as in the case of the two-surface corner reflector, the orientation and the imaging position are irrelevant even if they are arranged in a plurality of directions. In the unit optical element having two mirror surfaces that are not parallel, there are transmitted light of one reflection and non-reflected transmission light in addition to the reflection of two times. Become. Of these, the non-reflected transmitted light is transmitted in a direction substantially perpendicular to the element surface, so there is little possibility of direct interference with the twice reflected light transmitted at an angle. On the other hand, since the once reflected light is transmitted and imaged at a certain angle, there is a high possibility of interference. To solve this problem, when the unit optical element is arranged, it is possible to avoid image formation due to a single reflection by arranging the unit optical element in an arbitrary rotation direction around an axis orthogonal to the element surface. Can be reduced. In addition, when the individual unit optical elements are directed in different directions, the effect of widening the viewing angle by combining them is also brought about, but on the other hand, it becomes difficult to manufacture and the transmittance of the imaging element of the light is reduced. In such a case, it is preferable to arrange all unit optical elements in the same direction.

  In order to transmit light through the element surface while appropriately bending the light beam in the unit optical element, the unit optical element may be considered to use the inner wall of an optical hole assumed in the direction penetrating the element surface as a mirror surface. . However, such a unit optical element is a conceptual object and does not necessarily reflect a shape determined by a physical boundary or the like. For example, the optical holes are not independent of each other. It can be connected.

  If the structure of the optical element is simply described, a large number of mirror surfaces substantially perpendicular to the element surface are arranged on the element surface. The problem as a structure is how to support and fix the mirror surface to the element surface. As a more specific method of forming a mirror surface, for example, the imaging element of the present invention is provided with a base that partitions a predetermined space, and a single plane passing through the base is defined as an element surface. The element can be used as an optical hole assumed in the direction penetrating the element surface, and the inner wall of the hole formed in the substrate can be used as a mirror surface. The hole formed in the substrate only needs to be transparent so that light can pass through, and may be, for example, a vacuum filled with a transparent gas or liquid. Also, the shape of the hole may be any shape as long as the inner wall has one or more mirror surfaces not acting on the same plane for acting as a unit optical element, and the light reflected by the mirror surface can pass through the holes. It is possible to take a complicated shape in which each hole is connected or a part of the hole is missing. For example, an aspect in which individual mirror surfaces stand on the surface of the base can be understood as connecting holes formed in the base.

  Or a unit optical element may utilize the cylindrical body formed with solids, such as transparent glass and resin, as an optical hole. In addition, when each cylindrical body is formed of solid, these cylindrical bodies may be brought into close contact with each other and serve as a support member for the element, and project from the surface of the base as having a base. You may take the aspect which did. As for the shape of the cylindrical body, as long as the inner wall has a mirror surface not included in one or a plurality of coplanar surfaces to serve as a unit optical element, and the light reflected by the mirror surface can pass through the cylindrical body, Although it is possible to take an arbitrary shape, it may be a complicated shape in which each cylindrical body is connected or partially missing although it is referred to as a cylindrical body.

  Here, as the optical hole, a shape in which the adjacent inner wall surfaces are all orthogonal, such as a cube or a rectangular parallelepiped, can be considered. In this case, the interval between the unit optical elements can be minimized, and a high-density arrangement is possible. Further, if all the inner wall surfaces are mirror surfaces, four sets of two-surface corner reflectors facing different directions can be formed in one hole, and an imaging element that can be observed from various directions can be configured. . However, the presence of parallel and opposing mirror surfaces increases the possibility of unwanted multiple reflections.

  When there are a plurality of mirror surfaces in the unit optical element, there is a possibility that there is multiple reflected transmitted light that causes reflection more than the expected number of times. As a countermeasure against this multiple reflection, when two mirror surfaces orthogonal to each other are formed on the inner wall of the optical hole, the surfaces other than these two mirror surfaces are made non-mirror surfaces so that light is not reflected, By providing an angle or providing a curved surface so as not to be vertical, it is possible to reduce or eliminate multiple reflected light that causes three or more reflections. In order to obtain a non-mirror surface, it is possible to employ a configuration in which the surface is covered with an antireflection coating or a thin film, or a configuration in which the surface roughness is roughened to cause irregular reflection.

  In addition, since the presence of a transparent and flat substrate does not hinder the function of the optical element, the substrate can be arbitrarily used as a support member / protective member.

  Furthermore, in order to increase the definition of the image of the projection object, it is desirable to arrange the plurality of unit optical elements with as little spacing as possible on the element surface. For example, it is effective to arrange them in a grid pattern. is there. Further, in this case, there is an advantage that manufacture is also facilitated.

  As a mirror surface in the unit optical element, it is reflected by a flat surface formed of a glossy substance such as a metal or a resin regardless of whether it is solid or liquid, or flat between transparent media having different refractive indexes. It is possible to use a material that reflects or totally reflects on the boundary surface. Further, when the mirror surface is configured by total reflection, undesired multiple reflection by a plurality of mirror surfaces is likely to exceed the critical angle of total reflection, so that it can be expected to be naturally suppressed.

  The mirror surface may be formed on a very small part of the inner wall of the optical hole as long as there is no functional problem, or may be constituted by a plurality of unit mirror surfaces arranged in parallel. In other words, the latter aspect means that one mirror surface may be divided into a plurality of unit mirror surfaces. In this case, the unit mirror surfaces do not necessarily have to be on the same plane as long as they are parallel to each other. Further, each unit mirror surface is allowed to be either in contact with or apart from each other. When the imaging element of the present invention is configured as a reflective real mirror image imaging element, a two-surface corner reflector with two orthogonal mirror surfaces is required. Two mirror surfaces must be formed. The two mirror surfaces that are orthogonal to each other are not necessarily in contact with each other. When light is transmitted from one side of the element surface to the other side, it is only necessary to reflect each of the two mirror surfaces once. Either a mode in which the mirror surfaces are in contact with each other or a mode in which they are separated is allowed.

  The imaging element as described above is used as an object that forms an object as a real image in the opposite direction of the element surface, which is an object arranged on one side of the element surface or a projected image of a display device. Is possible. Here, “the direction opposite to the element surface” is intended to include a position that is plane-symmetric with respect to the element surface and a position that is not plane-symmetric. In particular, an aspect in which the projection target is imaged at a plane-symmetrical position opposite to the element surface is realized when the unit optical element includes a two-surface corner reflector, and two mirror surfaces constituting the two-surface corner reflector are formed. When tilted from the perpendicular to the element surface, the image forming point shifts from the plane symmetry position.

The display device according to the present invention includes a main body portion comprising an imaging element described above, the object to be projected which is arranged at any position definitive on the back side of the main body portion, emitted from the object to be projected The light to be transmitted is transmitted through the imaging element so that a real image of the projection object is formed and projected in a space on the surface side of the main body. Here, the projection object includes an object and an image displayed on an image display device such as a screen or a display. In particular, the formation and projection of a real image onto a plane-symmetric position with respect to the element surface of the projection object can be suitably realized when the imaging element includes the above-described two-plane corner reflector.

  With such a display device, it is possible to obtain the function and effect produced by the above-described imaging element, and it becomes a new and useful display device. For example, a desk top plate is used as a main body having the above-described imaging element, and an object or video display device is arranged as a projection object or an image is projected in a space under the top plate, thereby forming an imaging element. An image of the projection object can be projected in the air on the top board through the child. In addition, a building structure such as a wall, floor, or ceiling, partitions, screens, curtains, screens, and other fixtures are used as the main body with imaging elements, and the object that is the projection object is placed in the space behind it. It is also possible to show an image that jumps out into the air from a wall or partition by projecting or projecting the image. In addition, since any object can be used as the projection object, it is possible to generate a moving aerial image without using a video display device by moving the entity behind the imaging element. Even if the projection object is a three-dimensional object, an image can be formed without distortion although the depth in the line-of-sight direction is reversed. For depth reversal, an aerial image with a normal depth can be displayed by reversing the depth of a 3D object or 3D image in advance.

  As described above, according to the present invention, while simplifying the structure, reducing the cost, and reducing the thickness, any three-dimensional or two-dimensional object or image is aerial as a real image of a three-dimensional image or a two-dimensional image. It is possible to form an image on the element surface and observe the element surface at an angle from an oblique direction.

1 is a perspective view schematically showing a reflective real mirror image forming element according to an embodiment of an image forming element of the present invention. FIG. FIG. 3 is a plan view schematically showing a reflective real mirror image forming element of the embodiment. The A partial enlarged view of FIG. The expansion perspective view of the A section. The figure which shows typically the image formation style of the reflection type real mirror image formation element. The figure which shows typically the display apparatus provided with the reflection type real mirror image formation element based on the embodiment. The figure which shows typically the state imaged by applying a solid object as a to-be-projected object by the display apparatus. The perspective view which shows the reflection type real mirror image formation element which concerns on the one modification of the embodiment corresponding to FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 to 4, the imaging element X according to the present embodiment includes a first inner wall surface and a second inner wall surface, which are two inner wall surfaces penetrating in the thickness direction and orthogonal to the base 1. A plurality of unit optical elements 2 having mirror surfaces 21 and 22 are provided to have a function as a reflection type real mirror image forming element. Hereinafter, the reflection type real mirror image forming element will be described with reference numeral X as necessary. That is, as shown in FIG. 1, the reflection type real mirror image forming element X has a surface passing through the central portion of the thickness of the substrate 1 in parallel with the surface of the substrate 1 as an element surface S. The real image of the projection object O arranged in the space on one side (in the illustrated example, the back surface side of the substrate 1) corresponds to the element surface S in the space on the other side of the element surface S (in the illustrated example, the surface side of the substrate 1). It has the effect of forming an image as a mirror image P at a plane symmetry position. Here, in the present embodiment, the unit optical element 2 having a two-surface corner reflector 20 by two orthogonal mirror surfaces 21 and 22 is employed. In FIG. 1, since the mirror surfaces 21 and 22 are finer than the base 1, the entire set of unit optical elements 2 is expressed in gray, and the direction of the inner angle of the two-surface corner reflector 20 is expressed in a V shape. .

  Each unit optical element 2 is a physical and optical hole through which light passes. In addition, since this hole is fine with respect to the base | substrate 1, in FIGS. 2-4, the hole is expanded and exaggerated and shown. In this embodiment, a hole having a substantially rectangular shape (specifically, a square shape) in plan view is applied as the unit optical element 2, and the first inner wall surface and the second inner wall surface that are orthogonal to each other are mirror-finished. The two-sided corner reflector 20 is configured by causing the first inner wall surface and the second inner wall surface to function as mirror surfaces 21 and 22 which are reflecting surfaces. When the third inner wall surface 23 and the fourth inner wall surface 24 are also mirror-finished, four two-sided corner reflectors are formed, and a real image can be observed from a plurality of directions, but stray light due to multiple reflection also occurs. become. In order to prevent this stray light, the third inner wall surface 23 and the fourth inner wall surface 24 are made non-reflective surfaces, or the third inner wall surface 23 and the fourth inner wall surface 24 are at angles other than perpendicular to the element surface S. May be formed so as not to be parallel to the mirror surfaces 21 and 22 of the first inner wall surface and the second inner wall surface.

  In this embodiment, in order to perform observation from the side direction of the rectangular base 1, each side extending in the vertical and horizontal directions of each unit optical element 2 is inclined 45 degrees with respect to the width direction or depth direction of the base 1. In order to simplify the production, any two different unit optical elements 2 are made parallel to each other. That is, the unit optical elements 2 are formed on the base 1 so that the internal angles formed by the two mirror surfaces 21 and 22 constituting the dihedral corner reflector 20 in all the unit optical elements 2 face the same direction. However, ideally, it is better to have various (random) angles rather than parallel. By setting the angle, (1) the reflected light is diffused without forming an image, and (2) the lateral viewing angle of the reflected light is widened, and the peak of the transmittance with respect to the viewing angle becomes flat. is there. Note that the distance between adjacent unit optical elements 2 is set as small as possible. A portion of the base 1 other than the portion where the unit optical element 2 is formed is subjected to a light shielding process. Moreover, a transparent reinforcing material having a thin plate shape (not shown) can be provided on the upper surface and the lower surface of the substrate 1. It goes without saying that each unit optical element 2 is not optically sealed with this plate material. In the present embodiment, for example, tens of thousands to hundreds of thousands of such unit optical elements 2 are provided on a 5 cm square substrate 1.

  The unit optical element 2 formed on the base 1 in this way reflects light entering the hole constituting the unit optical element 2 from one surface (21 or 22) from the front side (or back side) of the base 1. In addition, the reflected light is reflected by the other mirror surface (22 or 21) and passed to the back surface side (or front surface side) of the substrate 1. FIG. 5 shows a projection of this light path on the element surface S. The double reflection of light by the two-surface corner reflector 20 is retroreflected in the element surface S, and the incident path and the emission path are parallel to each other in opposite directions. In addition, since the light component perpendicular to the element surface S is not converted at all, the light emitted from the point light source O can pass through a position that is substantially plane-symmetric with respect to the element surface S. I understand. The distance between the parallel incident path and output path in the element surface S is about the opening of the two-surface corner reflector 20, and further, it is divided into left and right depending on which mirror surface is used for the first reflection. When the light emitted from the point light source O passes through a plane symmetric with respect to the element surface S, it is about twice as large as the opening of the dihedral corner reflector 20, that is, the size of the mirror surface (21 or 22). √2 times (2 times the square root of 2) In other words, it spreads to about 3 times. The retroreflection by the two-surface corner reflector 20 occurs regardless of the angle of the incident light, and the light from all directions is emitted from the point light source. Therefore, the light passes through different unit optical elements 2 and is all the same. As a reflection type real mirror image forming element X, a large number of unit optical elements 2 having a dihedral corner reflector 20 are formed on the base 1 as described above. Function. That is, the element surface S of such a reflective real mirror image forming element X (assuming a plane that passes through the central portion of the thickness of the substrate 1 and is orthogonal to each mirror element as described above, is indicated by an imaginary line in the figure. .) Is a surface on which a real image of the projection object O on one side of the base 1 is imaged as a mirror image P at a plane symmetrical position on the other side. In addition, since the twice reflected light transmitted through the unit optical element 2 is focused on a plane-symmetrical position regardless of the distance from the element surface S, even a three-dimensional object is imaged as a mirror image P without distortion. Is possible. However, this image is equivalent to the case where the mirror image enters the mirror and is viewed from the back side, and the depth is inverted.

  In the present embodiment, each unit optical element 2 has a side of, for example, 50 to 1000 μm, preferably 100 μm in this embodiment. As shown in FIG. 4, the substrate 1 is a thin flat plate having a thickness dimension of 50 to 1000 μm, for example, 100 μm in this embodiment. Note that one side of the unit optical element defines the width of the mirror surfaces 21 and 22, and the thickness of the base defines the height of the mirror surfaces 21 and 22. In this embodiment, each mirror surface has dimensions approximately equal in width and height. ing.

  The size of the unit optical element 2 defines the resolution. As shown in FIG. 5, the point light source spreads about twice as large as the unit optical element 2 in terms of geometric optics. And concentrate. If it is made small, it can be focused on a small spot in terms of geometric optics, but it is strongly affected by diffraction, and if it is too small, the resolution deteriorates. Therefore, it is necessary to set the optimal size according to the distance to collect light. In this embodiment, the distance is optimized to about 1 to 2 cm.

  For the height of the mirror surfaces 21 and 22, that is, the thickness of the base 1 in this embodiment, the ratio with the size of the unit optical element 2 defines the optimum observation angle. As the thickness increases, the optimum observation angle becomes more suitable for observation from the direction perpendicular to the element surface S, and vice versa as the thickness decreases. In the case of the present embodiment, the ratio is 1: 1, and observation from 30 to 40 degrees above the horizontal direction is optimal. Further, the width dimension and depth dimension of the substrate 1 can be arbitrarily set since the structure of the imaging element X is uniform and there is no optical axis such as a convex lens or a concave mirror. About this magnitude | size, what is necessary is just to determine according to the magnitude | size of the object to image like a plane mirror.

  Next, a specific manufacturing method will be described. In this embodiment, a cylindrical body aligned with a metal mold by nano machining is first created, and a smooth mirror surface is formed on the side surfaces corresponding to the first inner wall surface and the second inner wall surface with a surface roughness of 50 nm or less. I do. Then, each unit optical element is formed as a plurality of holes at a predetermined pitch on one substrate 1 by reversal transfer by a nanoimprint method or an electroforming method using the previously created mold. In addition, when the base 1 is formed of a metal such as aluminum or nickel by the electroforming method, the first inner wall surface and the second inner wall surface are naturally mirror surfaces 21, if the surface roughness of the mold is sufficiently small. 22 Further, when the substrate 1 is made of resin or the like using the nanoimprint method, the first inner wall surface and the second inner wall surface need to be mirror-coated by sputtering or the like.

  The light transmitted through the reflection type real mirror image forming element X includes direct light that is not reflected by the two-surface corner reflector 20 constituted by the mirror surfaces 21 and 22 of the first inner wall surface and the second inner wall surface, and two-surface corner reflector. One reflected light that reflects only once on any one of the two mirror surfaces 21 and 22 of 20, a total of two times, once for each of the two mirror surfaces 21 and 22 of the two-surface corner reflector 20 There are reflected twice reflected light, two mirror surfaces 21 and 22 of the two-sided corner reflector 20, and multiple reflected light that causes reflection three times or more in total on the third inner wall surface 23 or the fourth inner wall surface 24. However, only the two-time reflected light among those lights is related to the formation of the real image of the mirror image.

  In addition, light other than the twice reflected light has characteristics different from the twice reflected light, and may become a stray light and hinder the use of the imaging element as the reflective real mirror image forming element X. . Therefore, a countermeasure against light other than the twice reflected light will be described.

  First, since direct light is observed within a relatively narrow range in the vertical direction with respect to the element surface S of the reflective real mirror image forming element X, a viewpoint with an oblique angle with respect to the element surface S. This is not a problem for the real image of the mirror image observed from above.

  When analyzing the intensity distribution of the one-time reflected light, the maximum is the direction facing the mirror surface 21 or 22, and there is a shift of 45 degrees from the direction where the maximum intensity is obtained by image formation by the two-surface corner reflector 20. Therefore, this is not a problem for a narrow range of viewpoints, but once reflected light is imaged in a different manner from twice reflected light. Will be. For this, there are measures such as rotating each two-sided corner reflector 20 randomly within the element surface S.

  In addition, since the multiple reflected light of three or more times has a problem of reflection on the opposite surface, the mirror surfaces 21 and 22 formed on the first inner wall surface and the second inner wall surface when the above-described oblique arrangement is performed. The inner wall surfaces (the third inner wall surface 23 and the fourth inner wall surface 24) that face each other can be avoided or reduced by not using a mirror surface or parallel.

  As shown in FIG. 6, the display device D according to the present embodiment includes one or a plurality of reflection type real mirror image forming elements X embedded in a horizontal posture on a top plate T that is a main body unit. The object to be projected O, which is a two-dimensional or three-dimensional object displayed or arranged in the space on the lower surface side, is connected to a position that is plane-symmetric with respect to the surface direction of the substrate 1 (more specifically, with respect to the element surface S). It is something to be imaged. In the figure, a display body H such as a liquid crystal display, which is an example of a video display device, is arranged as a projection object O in a substantially vertical posture with respect to the surface direction of the top board T in the space below the top board T. The form which displayed the character (the Roman letter "A") on the body H is illustrated.

  Next, the operation of the display device D will be described. As described above, the twice-reflected light transmitted through the unit optical element 2 is focused on a plane-symmetrical position, and therefore, with respect to the depth direction (direction perpendicular to the element surface S of the reflective real mirror image forming element X). It becomes possible to focus on a wide range, and light emitted from the projection object O, which is a two-dimensional image displayed on the display body H below the top plate T, is above the top plate T that does not physically exist. An image is formed as a mirror image P on an upright virtual display (phantom display), and the mirror image P can be observed from a viewpoint V from an oblique angle with respect to the element surface S. As shown in FIG. 7, for example, if a cylindrical three-dimensional image is arranged as the projection object O in the space on the lower surface side of the substrate 1, the three-dimensional image floats on the upper surface side of the substrate 1. However, the three-dimensional image P is observed as if the irregularities in the line-of-sight direction are reversed and the inner surface side of the cylinder is visible. In order to avoid such reversal of the unevenness of the projection object O and the image P, the unevenness of the three-dimensional image arranged in the space on the lower surface side of the substrate 1 may be reversed with respect to the element surface S in advance.

  As described above, the imaging element according to the present embodiment, that is, the reflective real mirror image imaging element X has two inner wall surfaces (first inner wall surface, second inner wall surface) penetrating the substrate 1 in the thickness direction and orthogonal to each other. ) Are provided with a plurality of unit optical elements 2 having two-surface corner reflectors 20 having mirror surfaces 21 and 22, so that two inner wall surfaces orthogonal to each other when passing through each unit optical element 2 are mirror surfaces 21 and 22. The light reflected twice in total passes through a point that is plane-symmetric with respect to the element surface S (that is, the surface direction of the substrate X1), so that the light is disposed in the space on one side of the substrate 1 (element surface S). Projection object O (two-dimensional or three-dimensional object or image) can be formed as a non-distorted two-dimensional image or a real image of a three-dimensional image in the other space, and the two-dimensional image and the three-dimensional image can be physically formed. It is possible to move to a space where no real entity exists. In addition, a virtual three-dimensional image or two-dimensional image imaged through the reflective real mirror image forming element X can be touched or pointed with a finger or the like, and an unprecedented and useful usage mode has been realized. can do. In particular, in this embodiment, since the imaging element can be used as the reflective real mirror image imaging element X, compared with the conventional refractive real mirror image imaging element using a plurality of microlenses, A real image of the object O can be observed as a mirror image P from an oblique angle with respect to the element surface S. Further, the structure can be simplified and the cost can be reduced, and the thickness can be reduced, so that various usage modes can be flexibly dealt with. In particular, since the unit optical element 2 applied in the present embodiment is a hole that penetrates in the thickness direction of the base X1, the refractive index can be changed by filling the hole with a transparent gas or liquid. .

  In addition, this invention is not limited to embodiment mentioned above. The two-surface corner reflector constituting the reflection type real mirror image forming element only needs to have two orthogonal reflecting surfaces, and this reflecting surface has a flatness with a mirror accuracy of a material that reflects light. Phenomena such as reflection by an end face or a film and total reflection at a boundary having a flatness of mirror surface accuracy between transparent media having different refractive indexes can be used. More specifically, in the above-described embodiment, in the reflective real mirror image forming element X, a square hole is formed in the thin plate-like base 1, and two adjacent inner peripheral walls of the hole are mirror surfaces. Although the example which formed the double-sided corner reflector 20 as 21 and 22 was shown, for example, it changed into such a structure and, as shown in FIG. 8, by the transparent cylindrical body which protrudes in the thickness direction of base | substrate 1 ', The unit optical element 2 ′ may be configured, and a reflective real mirror image forming element X ′ in which a large number of such cylindrical bodies are formed in a grid pattern may be used. In this case, the two-surface corner reflector 20 ′ can be configured with the first inner wall surface and the second inner wall surface that are orthogonal among the inner wall surfaces of each cylindrical body 2 ′ as mirror surfaces 21 ′ and 22 ′. In this case, similarly to the above-described embodiment, the light reflected twice by the two-surface corner reflector 20 ′ passes through a point that is plane-symmetric with respect to the surface direction of the substrate 1 ′, that is, the element surface S ′. It is possible to form not only a two-dimensional image but also a three-dimensional image in the space.

  The third inner wall surface 23 ′ and the fourth inner wall surface 24 ′ other than the mirror surfaces 21 ′ and 22 ′ of the cylindrical body are not mirror surfaces, or are provided with an angle other than perpendicular to the element surface S. It is possible to obtain a clearer image without excessive reflection. The two mirror surfaces 21 ′ and 22 ′ constituting the two-surface corner reflector 20 ′ can use total reflection or can use reflection by a reflection film. In particular, when the total reflection of the mirror surfaces 21 ′ and 22 ′ is used, it is expected that multiple reflections are unlikely to occur because there is a critical angle in total reflection. Furthermore, it is also possible to attach a metal reflection film to two surfaces of a cylindrical body on which a mirror surface is to be formed, and bond the cylindrical bodies to each other. In this case, it is necessary to take measures against multiple reflection such as non-specularization on a surface other than the mirror surface, but it is possible to obtain a reflection type real mirror image forming element having a high aperture ratio and a high transmittance.

  In addition, the two mirror surfaces constituting the two-surface corner reflector may be arranged with a gap between each other without contacting each other as long as two orthogonal reflecting surfaces can be formed. There are no particular restrictions on the angle between the two surfaces that function as mirror surfaces constituting the two-surface corner reflector in the body and the other surfaces. As the unit optical element, a plane shape having a polygonal shape other than a rectangular shape, a triangular shape, or a surface connecting the ends of the two mirror surfaces opposite to each other at an intersection is substantially a partial arc shape in plan view. It doesn't matter. When the planar shape of the unit optical element is a right triangle, it means that a right angle prism is used as the unit optical element.

  Furthermore, the shape and size of the imaging element (including the reflective real mirror image imaging element), the thickness dimension of the base, the planar shape, the material, and the like may be changed as appropriate in accordance with various usage modes.

  In addition, the specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

  The imaging element of the present invention (including the reflective real mirror image imaging element) inverts the depth direction in the line-of-sight direction as a real image of a projection object placed on one side of the element surface in a space without a physical entity on the other side. Since the optical element has a new imaging action of forming an image, it can be used as an image display device such as a display or an observation device such as an exhibit.

Claims (20)

An optical element that causes bending of a light beam when light is transmitted through an element surface constituting one plane,
The unit optical element that functions as a dihedral corner reflector that performs reflection of light by the two mirror surfaces to be substantially perpendicular to each other which are arranged in a vertical or an angle close thereto on the element surface and a plurality placed, whereas across the element surface when the light beam emitted from the object to be projected, which is located at any position in space of the side passes through the respective unit optical elements, once in each of the two mirror in each unit optical element, it reflects a total of two Accordingly, an image of the projection object is formed at a plane-symmetrical position of the projection object with respect to the element surface, and the imaging is performed from a viewpoint at an oblique angle with respect to the element surface. An imaging element characterized in that an image caused by twice reflection can be observed . The imaging element according to claim 1, wherein the two-surface corner reflector is arranged in a plurality of directions on the element surface . The imaging element according to claim 1 , wherein the two-surface corner reflectors are arranged in the same direction on the element surface . The imaging element according to claim 1, wherein the unit optical element uses an inner wall of an optical hole assumed in a direction penetrating the element surface as the mirror surface . 5. The imaging element according to claim 4, wherein the unit optical element is formed by connecting the optical holes without being independent of each other . A base that divides a predetermined space is provided, and one plane passing through the base is defined as the element surface, and the unit optical element is an optical hole assumed in a direction penetrating the element surface. 6. The imaging element according to claim 4, wherein an inner wall of a hole formed in the base is used as the mirror surface . The imaging unit according to claim 6 , wherein the unit optical element has a hole formed in a base filled with a transparent gas or liquid . The said unit optical element utilizes the cylindrical body comprised by transparent solid as an optical hole assumed in the direction which penetrates the said element surface . Imaging element. The image forming element according to claim 8, wherein the unit optical element is formed by bringing the cylindrical bodies into close contact with each other . The imaging element according to claim 4, wherein the optical hole has a cubic or rectangular parallelepiped shape . The imaging element according to claim 10 , wherein all four inner wall surfaces of the optical hole are mirror surfaces . The two mirror surfaces orthogonal to each other are formed on the inner wall of the optical hole, and surfaces other than the two orthogonal mirror surfaces on the inner wall are provided so as not to be perpendicular to the element surface . The imaging element according to any one of the above. The imaging element according to claim 4, wherein two mirror surfaces orthogonal to each other are formed on an inner wall of the optical hole, and a surface other than the two mirror surfaces orthogonal to each other on the inner wall is a non-mirror surface. . The imaging element according to claim 1, wherein the plurality of unit optical elements are arranged in a regular lattice shape on the element surface . The imaging element according to claim 1, wherein the mirror surface of the unit optical element uses reflection on a flat surface formed by a glossy substance . 16. The imaging element according to claim 1, wherein the mirror surface of the unit optical element uses reflection or total reflection at a flat boundary between transparent media having different refractive indexes . The imaging element according to any one of claims 1 to 16, wherein the mirror surface of the unit optical element includes a plurality of unit mirror surfaces arranged in parallel . A light emitted from the projection, comprising: a main body including the imaging element according to any one of claims 1 to 17; and a projection disposed at an arbitrary position on the back side of the main body. The display device is configured such that a real image of the object to be projected is formed and projected in a space on the surface side of the main body by transmitting the light through the imaging element. The display device according to claim 18, wherein the projection object is a three-dimensional image displayed on a three-dimensional object or an image display device in which a depth in a line-of-sight direction in which the real image is observed is inverted in advance. The display device according to claim 18, wherein the projection object is an object that operates automatically or by an external force, and projects an aerial image with movement in a space on the surface side of the main body as a real image of the object.

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